[kernel] add rt_thread_close()

* [thread] Add rt_thread_close()

This patch introduces a new function `rt_thread_close()` to enhances the
usability and maintainability by providing a dedicated mechanism for
closing threads.

- A new function `rt_thread_close()` is added to the API, providing a
  standardized approach for closing threads.
- The `rt_thread_close()` function removes a thread from the thread
  queue, updates its status to indicate closure, and performs the thread
  timer detaching which is a embedded timer in thread object.
- Additionally, the `rt_thread_detach()` function is modified to utilize
  `rt_thread_close()` internally, streamlining the thread detachment
  process.

Signed-off-by: Shell <smokewood@qq.com>

include/rtthread.h

@@ -160,6 +160,7 @@ rt_thread_t rt_thread_create(const char *name,
                              rt_uint8_t  priority,
                              rt_uint32_t tick);
 rt_err_t rt_thread_delete(rt_thread_t thread);
+rt_err_t rt_thread_close(rt_thread_t thread);
 #endif /* RT_USING_HEAP */
 rt_thread_t rt_thread_self(void);
 rt_thread_t rt_thread_find(char *name);